The present invention relates to an AC (Alternating Current) contactor and, more particularly, to an AC contactor in which, during the lowest potential of an AC source, its mechanical contacts are operated upon a large magnetic force converted from an instantaneous strong current in order to control the on or off of AC source load circuit and which may be controlled by external low voltage signal commands, thus providing safety protection from overload, phrase loss, short circuit, leakage current, etc.